Path Traversal in Frontaccounting
CVE-2026-40521
FrontAccounting before 2.4.20 contains a path traversal vulnerability in the attachment upload handler that allows authenticated attackers to execute arbitrary code by uploading files with traversal sequences in the unique_name parameter. Attackers can supply path traversal sequences ../../../shell.php to write files outside the intended attachments directory into the web root, and by uploading PHP files without extension validation, achieve remote code execution as the web server user.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.010 (61.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 61.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000
Affected products
- Frontaccounting — versions 0, 701fea6848da4a02fb83d30f07a9c0473d6b7e33
Weakness classification (CWE)
References
- jivasecurity.com/writeups/frontaccounting-rce-attachment-upload-cve-2026-40521 (technical-description, exploit)
- sourceforge.net/p/frontaccounting/news/2026/04/release-2420/ (release-notes)
- github.com/FrontAccountingERP/FA/commit/701fea6848da4a02fb83d30f07a9c0473d6b7e33 (patch)
- www.vulncheck.com/advisories/frontaccounting-path-traversal-rce-via-attachment-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-40521?
- CVE-2026-40521 is a high-severity vulnerability in Frontaccounting, classified under Path Traversal. CVSS score: 8.8/10. Published 2026-06-29.
- How severe is CVE-2026-40521?
- High severity. CVSS v3 base score is 8.8 out of 10.